1. Field of the Invention
The present invention relates to agricultural planters, and, more particularly, to agricultural planter row units.
2. Description of the Related Art
Agricultural planters are commonly used implements to plant seeds in soil. An agricultural planter can include a chassis that carries one or more storage tanks carrying seed, and chemical applications that are to be applied to the field during the planting operation, a hitch mechanism that attaches to a tractor or other implement pulled by a tractor, and a tool bar that row units can be connected to so they are carried by the chassis. The planter can also include a pneumatic system carried by the chassis that supplies pressurized air to transport the seeds or other particulate from the storage tanks to the row units.
Each row unit of the agricultural planter places seeds in the field. Typically, the row units are laterally arranged along a length of the tool bar so that as the planter is pulled across the field, each row unit plants seeds at predefined intervals along the path it is pulled across. To plant seeds, the row units perform four main operations as they are pulled: opening a trench in the soil; placing a seed into the formed trench at appropriate intervals; closing the formed trench to put soil on top of the placed seed; and packing soil on top of the seed to provide desirable soil contact with the placed seed. To open a trench in the soil, a furrowing disc system, which may include an opening disc, cuts into the soil and rotates, dislocating soil as it rotates to form the trench. Once the trench is open, a seed is placed in the trench by a metering device which receives seeds from the main storage tank(s) or a row unit storage tank and typically utilizes a combination of differential air pressure, to select the seed, and gravity to place the seed in the trench at predefined intervals along the pulled path so that adjacent seeds in the row are not too close to one another. One or more closing discs carried behind the furrowing disc are pressed into the soil and also rotate as the planter is pulled to replace soil dislocated by the furrowing disc in the trench or dislocate adjacent soil into the trench to cover the seed placed in the trench with soil. Finally, a pressing wheel carried behind the closing disc(s) exerts pressure on the soil covering the seed to press the soil down onto the seed and provide good soil contact with the seed. By having multiple row units working in unison as the planter is pulled across a field, many seeds can be effectively planted in an efficient manner.
To collapse the formed trench and cover the placed seed with soil, the closing disc(s) must be in contact with the soil. In order to keep continuous contact with the soil, a biasing element may be connected to the closing disc(s) to force the closing disc(s) into the soil and resist upward forces that occur during travel from lifting the closing disc(s) out of contact with the soil. One problem that can occur is that the closing disc(s) can bury itself due to excessive downward travel and pressing into the soil. This can lead to soil flow problems, disrupted seed placement and tear-out of the trench sidewall.
What is needed in the art is a way to limit the vertical travel of the closing disc(s).